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Schreiber R, Ousingsawat J, Kunzelmann K. The anoctamins: Structure and function. Cell Calcium 2024; 120:102885. [PMID: 38642428 DOI: 10.1016/j.ceca.2024.102885] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2024] [Revised: 04/03/2024] [Accepted: 04/04/2024] [Indexed: 04/22/2024]
Abstract
When activated by increase in intracellular Ca2+, anoctamins (TMEM16 proteins) operate as phospholipid scramblases and as ion channels. Anoctamin 1 (ANO1) is the Ca2+-activated epithelial anion-selective channel that is coexpressed together with the abundant scramblase ANO6 and additional intracellular anoctamins. In salivary and pancreatic glands, ANO1 is tightly packed in the apical membrane and secretes Cl-. Epithelia of airways and gut use cystic fibrosis transmembrane conductance regulator (CFTR) as an apical Cl- exit pathway while ANO1 supports Cl- secretion mainly by facilitating activation of luminal CFTR and basolateral K+ channels. Under healthy conditions ANO1 modulates intracellular Ca2+ signals by tethering the endoplasmic reticulum, and except of glands its direct secretory contribution as Cl- channel might be small, compared to CFTR. In the kidneys ANO1 supports proximal tubular acid secretion and protein reabsorption and probably helps to excrete HCO3-in the collecting duct epithelium. However, under pathological conditions as in polycystic kidney disease, ANO1 is strongly upregulated and may cause enhanced proliferation and cyst growth. Under pathological condition, ANO1 and ANO6 are upregulated and operate as secretory channel/phospholipid scramblases, partly by supporting Ca2+-dependent processes. Much less is known about the role of other epithelial anoctamins whose potential functions are discussed in this review.
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Affiliation(s)
- Rainer Schreiber
- Physiological Institute, University of Regensburg, University street 31, D-93053 Regensburg, Germany
| | - Jiraporn Ousingsawat
- Physiological Institute, University of Regensburg, University street 31, D-93053 Regensburg, Germany
| | - Karl Kunzelmann
- Physiological Institute, University of Regensburg, University street 31, D-93053 Regensburg, Germany.
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2
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Dibattista M, Pifferi S, Hernandez-Clavijo A, Menini A. The physiological roles of anoctamin2/TMEM16B and anoctamin1/TMEM16A in chemical senses. Cell Calcium 2024; 120:102889. [PMID: 38677213 DOI: 10.1016/j.ceca.2024.102889] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2024] [Revised: 04/11/2024] [Accepted: 04/17/2024] [Indexed: 04/29/2024]
Abstract
Chemical senses allow animals to detect and discriminate a vast array of molecules. The olfactory system is responsible of the detection of small volatile molecules, while water dissolved molecules are detected by taste buds in the oral cavity. Moreover, many animals respond to signaling molecules such as pheromones and other semiochemicals through the vomeronasal organ. The peripheral organs dedicated to chemical detection convert chemical signals into perceivable information through the employment of diverse receptor types and the activation of multiple ion channels. Two ion channels, TMEM16B, also known as anoctamin2 (ANO2) and TMEM16A, or anoctamin1 (ANO1), encoding for Ca2+-activated Cl¯ channels, have been recently described playing critical roles in various cell types. This review aims to discuss the main properties of TMEM16A and TMEM16B-mediated currents and their physiological roles in chemical senses. In olfactory sensory neurons, TMEM16B contributes to amplify the odorant response, to modulate firing, response kinetics and adaptation. TMEM16A and TMEM16B shape the pattern of action potentials in vomeronasal sensory neurons increasing the interspike interval. In type I taste bud cells, TMEM16A is activated during paracrine signaling mediated by ATP. This review aims to shed light on the regulation of diverse signaling mechanisms and neuronal excitability mediated by Ca-activated Cl¯ channels, hinting at potential new roles for TMEM16A and TMEM16B in the chemical senses.
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Affiliation(s)
- Michele Dibattista
- Department of Translational Biomedicine and Neuroscience, University of Bari A. Moro, 70121 Bari, Italy
| | - Simone Pifferi
- Department of Experimental and Clinical Medicine, Università Politecnica delle Marche, 60126 Ancona, Italy.
| | - Andres Hernandez-Clavijo
- Department of Chemosensation, Institute for Biology II, RWTH Aachen University, 52074 Aachen, Germany
| | - Anna Menini
- Neurobiology Group, SISSA, Scuola Internazionale Superiore di Studi Avanzati, 34136 Trieste, Italy.
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3
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Bartoš L, Menon AK, Vácha R. Insertases scramble lipids: Molecular simulations of MTCH2. Structure 2024; 32:505-510.e4. [PMID: 38377988 PMCID: PMC11001264 DOI: 10.1016/j.str.2024.01.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Revised: 11/30/2023] [Accepted: 01/24/2024] [Indexed: 02/22/2024]
Abstract
Scramblases play a pivotal role in facilitating bidirectional lipid transport across cell membranes, thereby influencing lipid metabolism, membrane homeostasis, and cellular signaling. MTCH2, a mitochondrial outer membrane protein insertase, has a membrane-spanning hydrophilic groove resembling those that form the lipid transit pathway in known scramblases. Employing both coarse-grained and atomistic molecular dynamics simulations, we show that MTCH2 significantly reduces the free energy barrier for lipid movement along the groove and therefore can indeed function as a scramblase. Notably, the scrambling rate of MTCH2 in silico is similar to that of voltage-dependent anion channel (VDAC), a recently discovered scramblase of the outer mitochondrial membrane, suggesting a potential complementary physiological role for these mitochondrial proteins. Finally, our findings suggest that other insertases which possess a hydrophilic path across the membrane like MTCH2, can also function as scramblases.
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Affiliation(s)
- Ladislav Bartoš
- CEITEC - Central European Institute of Technology, Masaryk University, Kamenice 5, 625 00 Brno, Czech Republic; National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kamenice 5, 625 00 Brno, Czech Republic
| | - Anant K Menon
- Department of Biochemistry, Weill Cornell Medical College, New York, NY 10065, USA
| | - Robert Vácha
- CEITEC - Central European Institute of Technology, Masaryk University, Kamenice 5, 625 00 Brno, Czech Republic; National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kamenice 5, 625 00 Brno, Czech Republic; Department of Condensed Matter Physics, Faculty of Science, Masaryk University, Kotlářská 2, 611 37 Brno, Czech Republic.
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4
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Zhang Y, Wu K, Li Y, Wu S, Warshel A, Bai C. Predicting Mutational Effects on Ca 2+-Activated Chloride Conduction of TMEM16A Based on a Simulation Study. J Am Chem Soc 2024; 146:4665-4679. [PMID: 38319142 DOI: 10.1021/jacs.3c11940] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2024]
Abstract
The dysfunction and defects of ion channels are associated with many human diseases, especially for loss-of-function mutations in ion channels such as cystic fibrosis transmembrane conductance regulator mutations in cystic fibrosis. Understanding ion channels is of great current importance for both medical and fundamental purposes. Such an understanding should include the ability to predict mutational effects and describe functional and mechanistic effects. In this work, we introduce an approach to predict mutational effects based on kinetic information (including reaction barriers and transition state locations) obtained by studying the working mechanism of target proteins. Specifically, we take the Ca2+-activated chloride channel TMEM16A as an example and utilize the computational biology model to predict the mutational effects of key residues. Encouragingly, we verified our predictions through electrophysiological experiments, demonstrating a 94% prediction accuracy regarding mutational directions. The mutational strength assessed by Pearson's correlation coefficient is -0.80 between our calculations and the experimental results. These findings suggest that the proposed methodology is reliable and can provide valuable guidance for revealing functional mechanisms and identifying key residues of the TMEM16A channel. The proposed approach can be extended to a broad scope of biophysical systems.
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Affiliation(s)
- Yue Zhang
- Warshel Institute for Computational Biology, School of Life and Health Sciences, School of Medicine, The Chinese University of Hong Kong (Shenzhen), Shenzhen 518172, China
- School of Chemistry and Materials Science, University of Science and Technology of China, Hefei 230026, China
| | - Kang Wu
- South China Hospital, Health Science Center, Shenzhen University, Shenzhen 518116, China
| | - Yuqing Li
- South China Hospital, Health Science Center, Shenzhen University, Shenzhen 518116, China
| | - Song Wu
- South China Hospital, Health Science Center, Shenzhen University, Shenzhen 518116, China
| | - Arieh Warshel
- Department of Chemistry, University of Southern California, Los Angeles, California 90089-1062, United States
| | - Chen Bai
- Warshel Institute for Computational Biology, School of Life and Health Sciences, School of Medicine, The Chinese University of Hong Kong (Shenzhen), Shenzhen 518172, China
- Chenzhu Biotechnology Co., Ltd., Hangzhou 310005, China
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5
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Kolesnikov DO, Nomerovskaya MA, Grigorieva ER, Reshetin DS, Skobeleva KV, Gusev KO, Shalygin AV, Kaznacheyeva EV. Calcium chelation independent effects of BAPTA on endogenous ANO6 channels in HEK293T cells. Biochem Biophys Res Commun 2024; 693:149378. [PMID: 38100999 DOI: 10.1016/j.bbrc.2023.149378] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2023] [Accepted: 12/09/2023] [Indexed: 12/17/2023]
Abstract
Selective calcium chelator 1,2-Bis(2-aminophenoxy) ethane-N,N,N',N'-tetraacetic acid (BAPTA) is a common tool to investigate calcium signaling. However, BAPTA expresses various effects on intracellular calcium signaling, which are not related to its ability to bind Ca2+. In patch clamp experiments, we investigated calcium chelation independent effects of BAPTA on endogenous calcium-activated chloride channels ANO6 (TMEM16F) in HEK293T cells. We have found that application of BAPTA to intracellular solution led to two distinct effects on channels properties. On the one hand, application of BAPTA acutely reduced amplitude of endogenous ANO6 channels induced by 10 μM Ca2+ in single channel recordings. On the other hand, BAPTA application by itself induced ANO6 channel activity in the absence of the intracellular calcium elevation. Open channel probability was enhanced by increasing the intracellular BAPTA concentration from 0.1 to 1 and 10 mM. Another calcium chelator EGTA did not demonstrate chelation independent effects on the ANO6 activity in the same conditions. Due to off-target effects BAPTA should be used with caution when studying calcium-activated ANO6 channels.
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Affiliation(s)
- D O Kolesnikov
- Institute of Cytology RAS, Tikhoretsky Ave. 4, St. Petersburg, 194064, Russian Federation
| | - M A Nomerovskaya
- Institute of Cytology RAS, Tikhoretsky Ave. 4, St. Petersburg, 194064, Russian Federation
| | - E R Grigorieva
- Institute of Cytology RAS, Tikhoretsky Ave. 4, St. Petersburg, 194064, Russian Federation
| | - D S Reshetin
- Institute of Cytology RAS, Tikhoretsky Ave. 4, St. Petersburg, 194064, Russian Federation
| | - K V Skobeleva
- Institute of Cytology RAS, Tikhoretsky Ave. 4, St. Petersburg, 194064, Russian Federation
| | - K O Gusev
- Institute of Cytology RAS, Tikhoretsky Ave. 4, St. Petersburg, 194064, Russian Federation
| | - A V Shalygin
- Institute of Cytology RAS, Tikhoretsky Ave. 4, St. Petersburg, 194064, Russian Federation.
| | - E V Kaznacheyeva
- Institute of Cytology RAS, Tikhoretsky Ave. 4, St. Petersburg, 194064, Russian Federation.
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6
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Ye Z, Galvanetto N, Puppulin L, Pifferi S, Flechsig H, Arndt M, Triviño CAS, Di Palma M, Guo S, Vogel H, Menini A, Franz CM, Torre V, Marchesi A. Structural heterogeneity of the ion and lipid channel TMEM16F. Nat Commun 2024; 15:110. [PMID: 38167485 PMCID: PMC10761740 DOI: 10.1038/s41467-023-44377-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Accepted: 12/11/2023] [Indexed: 01/05/2024] Open
Abstract
Transmembrane protein 16 F (TMEM16F) is a Ca2+-activated homodimer which functions as an ion channel and a phospholipid scramblase. Despite the availability of several TMEM16F cryogenic electron microscopy (cryo-EM) structures, the mechanism of activation and substrate translocation remains controversial, possibly due to restrictions in the accessible protein conformational space. In this study, we use atomic force microscopy under physiological conditions to reveal a range of structurally and mechanically diverse TMEM16F assemblies, characterized by variable inter-subunit dimerization interfaces and protomer orientations, which have escaped prior cryo-EM studies. Furthermore, we find that Ca2+-induced activation is associated to stepwise changes in the pore region that affect the mechanical properties of transmembrane helices TM3, TM4 and TM6. Our direct observation of membrane remodelling in response to Ca2+ binding along with additional electrophysiological analysis, relate this structural multiplicity of TMEM16F to lipid and ion permeation processes. These results thus demonstrate how conformational heterogeneity of TMEM16F directly contributes to its diverse physiological functions.
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Affiliation(s)
- Zhongjie Ye
- International School for Advanced Studies (SISSA), 34136, Trieste, Italy
- Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, 518055, Shenzhen, China
| | - Nicola Galvanetto
- Department of Physics, University of Zurich, 8057, Zurich, Switzerland
- Department of Biochemistry, University of Zurich, 8057, Zurich, Switzerland
| | - Leonardo Puppulin
- Department of Molecular Sciences and Nanosystems, Ca' Foscari University of Venice, I-30172 Mestre, Venice, Italy
- WPI Nano Life Science Institute, Kanazawa University, Kakuma-machi, 920-1192, Kanazawa, Japan
| | - Simone Pifferi
- International School for Advanced Studies (SISSA), 34136, Trieste, Italy
- Department of Experimental and Clinical Medicine, Università Politecnica delle Marche, 60126, Ancona, Italy
| | - Holger Flechsig
- WPI Nano Life Science Institute, Kanazawa University, Kakuma-machi, 920-1192, Kanazawa, Japan
| | - Melanie Arndt
- Department of Biochemistry, University of Zurich, 8057, Zurich, Switzerland
| | | | - Michael Di Palma
- Department of Experimental and Clinical Medicine, Università Politecnica delle Marche, 60126, Ancona, Italy
| | - Shifeng Guo
- Shenzhen Key Laboratory of Smart Sensing and Intelligent Systems, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China
- Guangdong Provincial Key Lab of Robotics and Intelligent System, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China
| | - Horst Vogel
- Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, 518055, Shenzhen, China
- Institut des Sciences et Ingénierie Chimiques (ISIC), Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Anna Menini
- International School for Advanced Studies (SISSA), 34136, Trieste, Italy
| | - Clemens M Franz
- WPI Nano Life Science Institute, Kanazawa University, Kakuma-machi, 920-1192, Kanazawa, Japan
| | - Vincent Torre
- International School for Advanced Studies (SISSA), 34136, Trieste, Italy.
- Institute of Materials (ION-CNR), Area Science Park, Basovizza, 34149, Trieste, Italy.
- BIoValley Investments System and Solutions (BISS), 34148, Trieste, Italy.
| | - Arin Marchesi
- WPI Nano Life Science Institute, Kanazawa University, Kakuma-machi, 920-1192, Kanazawa, Japan.
- Department of Experimental and Clinical Medicine, Università Politecnica delle Marche, 60126, Ancona, Italy.
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7
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Jahn H, Bartoš L, Dearden GI, Dittman JS, Holthuis JCM, Vácha R, Menon AK. Phospholipids are imported into mitochondria by VDAC, a dimeric beta barrel scramblase. Nat Commun 2023; 14:8115. [PMID: 38065946 PMCID: PMC10709637 DOI: 10.1038/s41467-023-43570-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2023] [Accepted: 11/13/2023] [Indexed: 12/17/2023] Open
Abstract
Mitochondria are double-membrane-bounded organelles that depend critically on phospholipids supplied by the endoplasmic reticulum. These lipids must cross the outer membrane to support mitochondrial function, but how they do this is unclear. We identify the Voltage Dependent Anion Channel (VDAC), an abundant outer membrane protein, as a scramblase-type lipid transporter that catalyzes lipid entry. On reconstitution into membrane vesicles, dimers of human VDAC1 and VDAC2 catalyze rapid transbilayer translocation of phospholipids by a mechanism that is unrelated to their channel activity. Coarse-grained molecular dynamics simulations of VDAC1 reveal that lipid scrambling occurs at a specific dimer interface where polar residues induce large water defects and bilayer thinning. The rate of phospholipid import into yeast mitochondria is an order of magnitude lower in the absence of VDAC homologs, indicating that VDACs provide the main pathway for lipid entry. Thus, VDAC isoforms, members of a superfamily of beta barrel proteins, moonlight as a class of phospholipid scramblases - distinct from alpha-helical scramblase proteins - that act to import lipids into mitochondria.
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Affiliation(s)
- Helene Jahn
- Department of Biochemistry, Weill Cornell Medical College, New York, NY, 10065, USA
| | - Ladislav Bartoš
- CEITEC - Central European Institute of Technology, Masaryk University, Kamenice 5, 62500, Brno, Czech Republic
- National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kamenice 5, 62500, Brno, Czech Republic
| | - Grace I Dearden
- Department of Biochemistry, Weill Cornell Medical College, New York, NY, 10065, USA
| | - Jeremy S Dittman
- Department of Biochemistry, Weill Cornell Medical College, New York, NY, 10065, USA
| | - Joost C M Holthuis
- Department of Molecular Cell Biology, University of Osnabrück, Osnabrück, 49076, Germany
| | - Robert Vácha
- CEITEC - Central European Institute of Technology, Masaryk University, Kamenice 5, 62500, Brno, Czech Republic.
- National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kamenice 5, 62500, Brno, Czech Republic.
| | - Anant K Menon
- Department of Biochemistry, Weill Cornell Medical College, New York, NY, 10065, USA.
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8
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Abstract
Scramblases play a pivotal role in facilitating bidirectional lipid transport across cell membranes, thereby influencing lipid metabolism, membrane homeostasis, and cellular signaling. MTCH2, a mitochondrial outer membrane protein insertase, has a membrane-spanning hydrophilic groove resembling those that form the lipid transit pathway in known scramblases. Employing both coarse-grained and atomistic molecular dynamics simulations, we show that MTCH2 significantly reduces the free energy barrier for lipid movement along the groove and therefore can indeed function as a scramblase. Notably, the scrambling rate of MTCH2 in silico is similar to that of VDAC, a recently discovered scramblase of the outer mitochondrial membrane, suggesting a potential complementary physiological role for these mitochondrial proteins. Finally, our findings suggest that other insertases which possess a hydrophilic path across the membrane like MTCH2, can also function as scramblases.
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Affiliation(s)
- Ladislav Bartoš
- CEITEC - Central European Institute of Technology, Masaryk University, Kamenice 753/5, 625 00 Brno, Czech Republic
- National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kamenice 753/5, 625 00 Brno, Czech Republic
| | - Anant K Menon
- Department of Biochemistry, Weill Cornell Medical College; New York, NY 10065, USA
| | - Robert Vácha
- CEITEC - Central European Institute of Technology, Masaryk University, Kamenice 753/5, 625 00 Brno, Czech Republic
- Department of Condensed Matter Physics, Faculty of Science, Masaryk University, Kotlarska 267/2, 611 37 Brno, Czech Republic
- National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kamenice 753/5, 625 00 Brno, Czech Republic
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9
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Balderas E, Lee SH, Shankar TS, Yin X, Balynas AM, Kyriakopoulos CP, Selzman CH, Drakos SG, Chaudhuri D. Mitochondria possess a large, non-selective ionic current that is enhanced during cardiac injury. bioRxiv 2023:2023.11.15.567241. [PMID: 38014208 PMCID: PMC10680780 DOI: 10.1101/2023.11.15.567241] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2023]
Abstract
Mitochondrial ion channels are essential for energy production and cell survival. To avoid depleting the electrochemical gradient used for ATP synthesis, channels so far described in the mitochondrial inner membrane open only briefly, are highly ion-selective, have restricted tissue distributions, or have small currents. Here, we identify a mitochondrial inner membrane conductance that has strikingly different behavior from previously described channels. It is expressed ubiquitously, and transports cations non-selectively, producing a large, up to nanoampere-level, current. The channel does not lead to inner membrane uncoupling during normal physiology because it only becomes active at depolarized voltages. It is inhibited by external Ca2+, corresponding to the intermembrane space, as well as amiloride. This large, ubiquitous, non-selective, amiloride-sensitive (LUNA) current appears most active when expression of the mitochondrial calcium uniporter is minimal, such as in the heart. In this organ, we find that LUNA current magnitude increases two- to threefold in multiple mouse models of injury, an effect also seen in cardiac mitochondria from human patients with heart failure with reduced ejection fraction. Taken together, these features lead us to speculate that LUNA current may arise from an essential protein that acts as a transporter under physiological conditions, but becomes a channel under conditions of mitochondrial stress and depolarization.
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Affiliation(s)
- Enrique Balderas
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT
| | - Sandra H.J. Lee
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT
| | - Thirupura S. Shankar
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT
| | - Xue Yin
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT
| | - Anthony M. Balynas
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT
| | - Christos P. Kyriakopoulos
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT
| | - Craig H. Selzman
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT
- Department of Surgery, Division of Cardiothoracic Surgery, University of Utah, Salt Lake City, UT
- U.T.A.H. (Utah Transplant Affiliated Hospitals) Cardiac Transplant Program: University of Utah Healthcare and School of Medicine, Intermountain Medical Center, Salt Lake Veterans Affairs Health Care System, Salt Lake City, UT
| | - Stavros G. Drakos
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT
- U.T.A.H. (Utah Transplant Affiliated Hospitals) Cardiac Transplant Program: University of Utah Healthcare and School of Medicine, Intermountain Medical Center, Salt Lake Veterans Affairs Health Care System, Salt Lake City, UT
- Department of Internal Medicine, Division of Cardiovascular Medicine, University of Utah, Salt Lake City, UT
| | - Dipayan Chaudhuri
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT
- U.T.A.H. (Utah Transplant Affiliated Hospitals) Cardiac Transplant Program: University of Utah Healthcare and School of Medicine, Intermountain Medical Center, Salt Lake Veterans Affairs Health Care System, Salt Lake City, UT
- Department of Internal Medicine, Division of Cardiovascular Medicine, University of Utah, Salt Lake City, UT
- Departments of Biochemistry, Biomedical Engineering, University of Utah, Salt Lake City, UT
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10
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Derudas M, O’Reilly M, Kirkwood NK, Kenyon EJ, Grimsey S, Kitcher SR, Workman S, Bull JC, Ward SE, Kros CJ, Richardson GP. Charge and lipophilicity are required for effective block of the hair-cell mechano-electrical transducer channel by FM1-43 and its derivatives. Front Cell Dev Biol 2023; 11:1247324. [PMID: 37900280 PMCID: PMC10601989 DOI: 10.3389/fcell.2023.1247324] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2023] [Accepted: 09/19/2023] [Indexed: 10/31/2023] Open
Abstract
The styryl dye FM1-43 is widely used to study endocytosis but behaves as a permeant blocker of the mechano-electrical transducer (MET) channel in sensory hair cells, loading rapidly and specifically into the cytoplasm of hair cells in a MET channel-dependent manner. Patch clamp recordings of mouse outer hair cells (OHCs) were used to determine how a series of structural modifications of FM1-43 affect MET channel block. Fluorescence microscopy was used to assess how the modifications influence hair-cell loading in mouse cochlear cultures and zebrafish neuromasts. Cochlear cultures were also used to evaluate otoprotective potential of the modified FM1-43 derivatives. Structure-activity relationships reveal that the lipophilic tail and the cationic head group of FM1-43 are both required for MET channel block in mouse cochlear OHCs; neither moiety alone is sufficient. The extent of MET channel block is augmented by increasing the lipophilicity/bulkiness of the tail, by reducing the number of positive charges in the head group from two to one, or by increasing the distance between the two charged head groups. Loading assays with zebrafish neuromasts and mouse cochlear cultures are broadly in accordance with these observations but reveal a loss of hair-cell specific labelling with increasing lipophilicity. Although FM1-43 and many of its derivatives are generally cytotoxic when tested on cochlear cultures in the presence of an equimolar concentration of the ototoxic antibiotic gentamicin (5 µM), at a 10-fold lower concentration (0.5 µM), two of the derivatives protect OHCs from cell death caused by 48 h-exposure to 5 µM gentamicin.
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Affiliation(s)
- Marco Derudas
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Brighton, United Kingdom
- Sussex Drug Discovery Centre, School of Life Sciences, University of Sussex, Brighton, United Kingdom
| | - Molly O’Reilly
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Brighton, United Kingdom
- Department of Experimental Cardiology, Academic Medical Center, Amsterdam, Netherlands
| | - Nerissa K. Kirkwood
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Brighton, United Kingdom
- School of Biosciences, University of Kent, Canterbury, United Kingdom
| | - Emma J. Kenyon
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Brighton, United Kingdom
- School of Medicine, Institute of Life Sciences, Swansea University, Swansea, United Kingdom
| | - Sybil Grimsey
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Brighton, United Kingdom
| | - Siân R. Kitcher
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Brighton, United Kingdom
- Section on Neuronal Circuitry, National Institute on Deafness and Other Communication Disorders NIH, Bethesda, MD, United States
| | - Shawna Workman
- Department of Biosciences, College of Science, Swansea University, Swansea, United Kingdom
| | - James C. Bull
- Department of Biosciences, College of Science, Swansea University, Swansea, United Kingdom
| | - Simon E. Ward
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Brighton, United Kingdom
- Medicines Discovery Institute, Cardiff University, Cardiff, United Kingdom
| | - Corné J. Kros
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Brighton, United Kingdom
| | - Guy P. Richardson
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Brighton, United Kingdom
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11
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Herrera SA, Günther Pomorski T. Reconstitution of ATP-dependent lipid transporters: gaining insight into molecular characteristics, regulation, and mechanisms. Biosci Rep 2023; 43:BSR20221268. [PMID: 37417269 PMCID: PMC10412526 DOI: 10.1042/bsr20221268] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Revised: 06/30/2023] [Accepted: 07/06/2023] [Indexed: 07/08/2023] Open
Abstract
Lipid transporters play a crucial role in supporting essential cellular processes such as organelle assembly, vesicular trafficking, and lipid homeostasis by driving lipid transport across membranes. Cryo-electron microscopy has recently resolved the structures of several ATP-dependent lipid transporters, but functional characterization remains a major challenge. Although studies of detergent-purified proteins have advanced our understanding of these transporters, in vitro evidence for lipid transport is still limited to a few ATP-dependent lipid transporters. Reconstitution into model membranes, such as liposomes, is a suitable approach to study lipid transporters in vitro and to investigate their key molecular features. In this review, we discuss the current approaches for reconstituting ATP-driven lipid transporters into large liposomes and common techniques used to study lipid transport in proteoliposomes. We also highlight the existing knowledge on the regulatory mechanisms that modulate the activity of lipid transporters, and finally, we address the limitations of the current approaches and future perspectives in this field.
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Affiliation(s)
- Sara Abad Herrera
- Department of Molecular Biochemistry, Faculty of Chemistry and Biochemistry, Ruhr University Bochum, Bochum, Germany
| | - Thomas Günther Pomorski
- Department of Molecular Biochemistry, Faculty of Chemistry and Biochemistry, Ruhr University Bochum, Bochum, Germany
- Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg, Denmark
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12
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Feng S, Puchades C, Ko J, Wu H, Chen Y, Figueroa EE, Gu S, Han TW, Ho B, Cheng T, Li J, Shoichet B, Jan YN, Cheng Y, Jan LY. Identification of a drug binding pocket in TMEM16F calcium-activated ion channel and lipid scramblase. Nat Commun 2023; 14:4874. [PMID: 37573365 PMCID: PMC10423226 DOI: 10.1038/s41467-023-40410-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2022] [Accepted: 07/23/2023] [Indexed: 08/14/2023] Open
Abstract
The dual functions of TMEM16F as Ca2+-activated ion channel and lipid scramblase raise intriguing questions regarding their molecular basis. Intrigued by the ability of the FDA-approved drug niclosamide to inhibit TMEM16F-dependent syncytia formation induced by SARS-CoV-2, we examined cryo-EM structures of TMEM16F with or without bound niclosamide or 1PBC, a known blocker of TMEM16A Ca2+-activated Cl- channel. Here, we report evidence for a lipid scrambling pathway along a groove harboring a lipid trail outside the ion permeation pore. This groove contains the binding pocket for niclosamide and 1PBC. Mutations of two residues in this groove specifically affect lipid scrambling. Whereas mutations of some residues in the binding pocket of niclosamide and 1PBC reduce their inhibition of TMEM16F-mediated Ca2+ influx and PS exposure, other mutations preferentially affect the ability of niclosamide and/or 1PBC to inhibit TMEM16F-mediated PS exposure, providing further support for separate pathways for ion permeation and lipid scrambling.
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Affiliation(s)
- Shengjie Feng
- Department of Physiology, University of California San Francisco (UCSF) School of Medicine, San Francisco, CA, USA
| | - Cristina Puchades
- Department of Biochemistry and Biophysics, University of California San Francisco (UCSF) School of Medicine, San Francisco, CA, USA
| | - Juyeon Ko
- Department of Physiology, University of California San Francisco (UCSF) School of Medicine, San Francisco, CA, USA
| | - Hao Wu
- Department of Biochemistry and Biophysics, University of California San Francisco (UCSF) School of Medicine, San Francisco, CA, USA
| | - Yifei Chen
- Howard Hughes Medical Institute; UCSF, San Francisco, CA, USA
| | - Eric E Figueroa
- Department of Physiology, University of California San Francisco (UCSF) School of Medicine, San Francisco, CA, USA
| | - Shuo Gu
- BioDuro-Sundia Inc., Irvine, CA, USA
| | - Tina W Han
- Department of Physiology, University of California San Francisco (UCSF) School of Medicine, San Francisco, CA, USA
- Dewpoint Therapeutics, Boston, MA, USA
| | - Brandon Ho
- Department of Physiology, University of California San Francisco (UCSF) School of Medicine, San Francisco, CA, USA
| | - Tong Cheng
- Howard Hughes Medical Institute; UCSF, San Francisco, CA, USA
| | - Junrui Li
- Department of Biochemistry and Biophysics, University of California San Francisco (UCSF) School of Medicine, San Francisco, CA, USA
| | - Brian Shoichet
- Department of Pharmaceutical Chemistry, University of California San Francisco (UCSF) School of Pharmacy, San Francisco, CA, USA
| | - Yuh Nung Jan
- Department of Physiology, University of California San Francisco (UCSF) School of Medicine, San Francisco, CA, USA
- Department of Biochemistry and Biophysics, University of California San Francisco (UCSF) School of Medicine, San Francisco, CA, USA
- Howard Hughes Medical Institute; UCSF, San Francisco, CA, USA
| | - Yifan Cheng
- Department of Biochemistry and Biophysics, University of California San Francisco (UCSF) School of Medicine, San Francisco, CA, USA.
- Howard Hughes Medical Institute; UCSF, San Francisco, CA, USA.
| | - Lily Yeh Jan
- Department of Physiology, University of California San Francisco (UCSF) School of Medicine, San Francisco, CA, USA.
- Department of Biochemistry and Biophysics, University of California San Francisco (UCSF) School of Medicine, San Francisco, CA, USA.
- Howard Hughes Medical Institute; UCSF, San Francisco, CA, USA.
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13
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Sperrhacke M, Leitzke S, Ahrens B, Reiss K. Breakdown of Phospholipid Asymmetry Triggers ADAM17-Mediated Rescue Events in Cells Undergoing Apoptosis. Membranes (Basel) 2023; 13:720. [PMID: 37623781 PMCID: PMC10456294 DOI: 10.3390/membranes13080720] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Revised: 07/27/2023] [Accepted: 08/03/2023] [Indexed: 08/26/2023]
Abstract
ADAM17, a prominent member of the "Disintegrin and Metalloproteinase" (ADAM) family, controls vital cellular functions through the cleavage of transmembrane substrates, including epidermal growth factor receptor (EGFR) ligands such as transforming growth factor (TGF)-alpha and Epiregulin (EREG). Several ADAM17 substrates are relevant to oncogenesis and tumor growth. We have presented evidence that surface exposure of phosphatidylserine (PS) is pivotal for ADAM17 to exert sheddase activity. The scramblase Xkr8 is instrumental for calcium-independent exposure of PS in apoptotic cells. Xkr8 can be dually activated by caspase-3 and by kinases. In this investigation, we examined whether Xkr8 would modulate ADAM17 activity under apoptotic and non-apoptotic conditions. Overexpression of Xkr8 in HEK293T cells led to significantly increased caspase-dependent as well as PMA-induced release of EREG and TGF-alpha. Conversely, siRNA-mediated downregulation of Xkr8 in colorectal Caco-2 cancer cells led to decreased PS externalization upon induction of apoptosis, which was accompanied by reduced shedding of endogenously expressed EREG and reduced cell survival. We conclude that Xkr8 shares with conventional scramblases the propensity to upmodulate the ADAM-sheddase function. Liberation of growth factors could serve a rescue function in cells on the pathway to apoptotic death.
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Affiliation(s)
| | | | | | - Karina Reiss
- Department of Dermatology, University of Kiel, 24105 Kiel, Germany (B.A.)
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14
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Zhang M, Shan Y, Cox CD, Pei D. A mechanical-coupling mechanism in OSCA/TMEM63 channel mechanosensitivity. Nat Commun 2023; 14:3943. [PMID: 37402734 DOI: 10.1038/s41467-023-39688-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Accepted: 06/23/2023] [Indexed: 07/06/2023] Open
Abstract
Mechanosensitive (MS) ion channels are a ubiquitous type of molecular force sensor sensing forces from the surrounding bilayer. The profound structural diversity in these channels suggests that the molecular mechanisms of force sensing follow unique structural blueprints. Here we determine the structures of plant and mammalian OSCA/TMEM63 proteins, allowing us to identify essential elements for mechanotransduction and propose roles for putative bound lipids in OSCA/TMEM63 mechanosensation. Briefly, the central cavity created by the dimer interface couples each subunit and modulates dimeric OSCA/TMEM63 channel mechanosensitivity through the modulating lipids while the cytosolic side of the pore is gated by a plug lipid that prevents the ion permeation. Our results suggest that the gating mechanism of OSCA/TMEM63 channels may combine structural aspects of the 'lipid-gated' mechanism of MscS and TRAAK channels and the calcium-induced gating mechanism of the TMEM16 family, which may provide insights into the structural rearrangements of TMEM16/TMC superfamilies.
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Affiliation(s)
- Mingfeng Zhang
- Fudan University, Shanghai, 200433, China.
- Laboratory of Cell Fate Control, School of Life Sciences, Westlake University, Hangzhou, 310000, China.
| | - Yuanyue Shan
- Fudan University, Shanghai, 200433, China
- Laboratory of Cell Fate Control, School of Life Sciences, Westlake University, Hangzhou, 310000, China
| | - Charles D Cox
- Victor Chang Cardiac Research Institute, Sydney, 2010, Australia.
- School of Biomedical Sciences, Faculty of Medicine & Health, UNSW Sydney, Kensington, New South Wales, 2052, Australia.
| | - Duanqing Pei
- Laboratory of Cell Fate Control, School of Life Sciences, Westlake University, Hangzhou, 310000, China.
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15
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Cevoli F, Arnould B, Peralta FA, Grutter T. Untangling Macropore Formation and Current Facilitation in P2X7. Int J Mol Sci 2023; 24:10896. [PMID: 37446075 DOI: 10.3390/ijms241310896] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Revised: 06/26/2023] [Accepted: 06/28/2023] [Indexed: 07/15/2023] Open
Abstract
Macropore formation and current facilitation are intriguing phenomena associated with ATP-gated P2X7 receptors (P2X7). Macropores are large pores formed in the cell membrane that allow the passage of large molecules. The precise mechanisms underlying macropore formation remain poorly understood, but recent evidence suggests two alternative pathways: a direct entry through the P2X7 pore itself, and an indirect pathway triggered by P2X7 activation involving additional proteins, such as TMEM16F channel/scramblase. On the other hand, current facilitation refers to the progressive increase in current amplitude and activation kinetics observed with prolonged or repetitive exposure to ATP. Various mechanisms, including the activation of chloride channels and intrinsic properties of P2X7, have been proposed to explain this phenomenon. In this comprehensive review, we present an in-depth overview of P2X7 current facilitation and macropore formation, highlighting new findings and proposing mechanistic models that may offer fresh insights into these untangled processes.
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Affiliation(s)
- Federico Cevoli
- Équipe de Chimie et Neurobiologie Moléculaire, Laboratoire de Conception et Application de Molécules Bioactives (CAMB) UMR 7199, Centre National de la Recherche Scientifique, Faculté de Pharmacie, Université de Strasbourg, 67401 Illkirch, France
| | - Benoit Arnould
- Équipe de Chimie et Neurobiologie Moléculaire, Laboratoire de Conception et Application de Molécules Bioactives (CAMB) UMR 7199, Centre National de la Recherche Scientifique, Faculté de Pharmacie, Université de Strasbourg, 67401 Illkirch, France
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Francisco Andrés Peralta
- Équipe de Chimie et Neurobiologie Moléculaire, Laboratoire de Conception et Application de Molécules Bioactives (CAMB) UMR 7199, Centre National de la Recherche Scientifique, Faculté de Pharmacie, Université de Strasbourg, 67401 Illkirch, France
- Instituto de Neurociencias, CSIC-UMH, 03550 San Juan de Alicante, Spain
| | - Thomas Grutter
- Équipe de Chimie et Neurobiologie Moléculaire, Laboratoire de Conception et Application de Molécules Bioactives (CAMB) UMR 7199, Centre National de la Recherche Scientifique, Faculté de Pharmacie, Université de Strasbourg, 67401 Illkirch, France
- University of Strasbourg Institute for Advanced Studies (USIAS), 67000 Strasbourg, France
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16
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Sakuragi T, Nagata S. Regulation of phospholipid distribution in the lipid bilayer by flippases and scramblases. Nat Rev Mol Cell Biol 2023:10.1038/s41580-023-00604-z. [PMID: 37106071 PMCID: PMC10134735 DOI: 10.1038/s41580-023-00604-z] [Citation(s) in RCA: 25] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/09/2023] [Indexed: 04/29/2023]
Abstract
Cellular membranes function as permeability barriers that separate cells from the external environment or partition cells into distinct compartments. These membranes are lipid bilayers composed of glycerophospholipids, sphingolipids and cholesterol, in which proteins are embedded. Glycerophospholipids and sphingolipids freely move laterally, whereas transverse movement between lipid bilayers is limited. Phospholipids are asymmetrically distributed between membrane leaflets but change their location in biological processes, serving as signalling molecules or enzyme activators. Designated proteins - flippases and scramblases - mediate this lipid movement between the bilayers. Flippases mediate the confined localization of specific phospholipids (phosphatidylserine (PtdSer) and phosphatidylethanolamine) to the cytoplasmic leaflet. Scramblases randomly scramble phospholipids between leaflets and facilitate the exposure of PtdSer on the cell surface, which serves as an important signalling molecule and as an 'eat me' signal for phagocytes. Defects in flippases and scramblases cause various human diseases. We herein review the recent research on the structure of flippases and scramblases and their physiological roles. Although still poorly understood, we address the mechanisms by which they translocate phospholipids between lipid bilayers and how defects cause human diseases.
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Affiliation(s)
- Takaharu Sakuragi
- Biochemistry & Immunology, WPI Immunology Frontier Research Center, Osaka University, Osaka, Japan
| | - Shigekazu Nagata
- Biochemistry & Immunology, WPI Immunology Frontier Research Center, Osaka University, Osaka, Japan.
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17
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Yuan L, Tang Y, Yin L, Lin X, Luo Z, Wang S, Li J, Liang P, Jiang B. The role of Transmembrane Protein 16A (TMEM16A) in pulmonary hypertension. Cardiovasc Pathol 2023; 65:107525. [PMID: 36781068 DOI: 10.1016/j.carpath.2023.107525] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Revised: 02/04/2023] [Accepted: 02/06/2023] [Indexed: 02/13/2023] Open
Abstract
Transmembrane protein 16A (TMEM16A), a member of the TMEM16 family, is the molecular basis of Ca2+-activated chloride channels (CaCCs) and is involved in a variety of physiological and pathological processes. Previous studies have focused more on respiratory-related diseases and tumors. However, recent studies have identified an important role for TMEM16A in cardiovascular diseases, especially in pulmonary hypertension. TMEM16A is expressed in both pulmonary artery smooth muscle cells and pulmonary artery endothelial cells and is involved in the development of pulmonary hypertension. This paper presents the structure and function of TMEM16A, the pathogenesis of pulmonary hypertension, and highlights the role and mechanism of TMEM16A in pulmonary hypertension, summarizing the controversies in this field and taking into account hypertension and portal hypertension, which have similar pathogenesis. It is hoped that the unique role of TMEM16A in pulmonary hypertension will be illustrated and provide ideas for research in this area.
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Affiliation(s)
- Ludong Yuan
- Department of Pathophysiology, Sepsis Translational Medicine Key Laboratory of Hunan Province, Xiangya School of Medicine, Central South University, Changsha, Hunan, China; National Medicine Functional Experimental Teaching Center, Central South University, Changsha, Hunan China
| | - Yuting Tang
- Department of Pathophysiology, Sepsis Translational Medicine Key Laboratory of Hunan Province, Xiangya School of Medicine, Central South University, Changsha, Hunan, China; National Medicine Functional Experimental Teaching Center, Central South University, Changsha, Hunan China
| | - Leijing Yin
- Department of Pathophysiology, Sepsis Translational Medicine Key Laboratory of Hunan Province, Xiangya School of Medicine, Central South University, Changsha, Hunan, China; National Medicine Functional Experimental Teaching Center, Central South University, Changsha, Hunan China
| | - Xiaofang Lin
- Department of Pathophysiology, Sepsis Translational Medicine Key Laboratory of Hunan Province, Xiangya School of Medicine, Central South University, Changsha, Hunan, China; National Medicine Functional Experimental Teaching Center, Central South University, Changsha, Hunan China
| | - Zhengyang Luo
- Department of Pathophysiology, Sepsis Translational Medicine Key Laboratory of Hunan Province, Xiangya School of Medicine, Central South University, Changsha, Hunan, China; National Medicine Functional Experimental Teaching Center, Central South University, Changsha, Hunan China
| | - Shuxin Wang
- Department of Pathophysiology, Sepsis Translational Medicine Key Laboratory of Hunan Province, Xiangya School of Medicine, Central South University, Changsha, Hunan, China; National Medicine Functional Experimental Teaching Center, Central South University, Changsha, Hunan China
| | - Jing Li
- Department of Pathophysiology, Sepsis Translational Medicine Key Laboratory of Hunan Province, Xiangya School of Medicine, Central South University, Changsha, Hunan, China; National Medicine Functional Experimental Teaching Center, Central South University, Changsha, Hunan China
| | - Pengfei Liang
- Department of Burns and Plastic Surgery, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Bimei Jiang
- Department of Pathophysiology, Sepsis Translational Medicine Key Laboratory of Hunan Province, Xiangya School of Medicine, Central South University, Changsha, Hunan, China; National Medicine Functional Experimental Teaching Center, Central South University, Changsha, Hunan China.
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18
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Metsälä O, Wahlström G, Taimen P, Kellokumpu-Lehtinen PL, Schleutker J. Transcripts of the Prostate Cancer-Associated Gene ANO7 Are Retained in the Nuclei of Prostatic Epithelial Cells. Int J Mol Sci 2023; 24. [PMID: 36674564 DOI: 10.3390/ijms24021052] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Revised: 01/02/2023] [Accepted: 01/03/2023] [Indexed: 01/06/2023] Open
Abstract
Prostate cancer affects millions of men globally. The prostate cancer-associated gene ANO7 is downregulated in advanced prostate cancer, whereas benign tissue and low-grade cancer display varying expression levels. In this study, we assess the spatial correlation between ANO7 mRNA and protein using fluorescent in situ hybridization and immunohistochemistry for the detection of mRNA and protein in parallel sections of tissue microarrays prepared from radical prostatectomy samples. We show that ANO7 mRNA and protein expression correlate in prostate tissue. Furthermore, we show that ANO7 mRNA is enriched in the nuclei of the luminal cells at 89% in benign ducts and low-grade cancer, and at 78% in high-grade cancer. The nuclear enrichment of ANO7 mRNA was validated in prostate cancer cell lines 22Rv1 and MDA PCa 2b using droplet digital polymerase chain reaction (ddPCR) on RNA isolated from nuclear and cytoplasmic fractions of the cells. The nuclear enrichment of ANO7 mRNA was compared to the nuclearly-enriched lncRNA MALAT1, confirming the surprisingly high nuclear retention of ANO7 mRNA. ANO7 has been suggested to be used as a diagnostic marker and a target for immunotherapy, but a full comprehension of its role in prostate cancer progression is currently lacking. Our results contribute to a better understanding of the dynamics of ANO7 expression in prostatic tissue.
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19
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Li J, Zhao Y, Wang N. Physiological and Pathological Functions of TMEM30A: An Essential Subunit of P4-ATPase Phospholipid Flippases. J Lipids 2023; 2023:4625567. [PMID: 37200892 PMCID: PMC10188266 DOI: 10.1155/2023/4625567] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Revised: 03/28/2023] [Accepted: 04/15/2023] [Indexed: 05/20/2023] Open
Abstract
Phospholipids are asymmetrically distributed across mammalian plasma membrane. The function of P4-ATPases is to maintain the abundance of phosphatidylserine (PS) and phosphatidylethanolamine (PE) in the inner leaflet as lipid flippases. Transmembrane protein 30A (TMEM30A, also named CDC50A), as an essential β subunit of most P4-ATPases, facilitates their transport and functions. With TMEM30A knockout mice or cell lines, it is found that the loss of TMEM30A has huge influences on the survival of mice and cells because of PS exposure-triggered apoptosis signaling. TMEM30A is a promising target for drug discovery due to its significant roles in various systems and diseases. In this review, we summarize the functions of TMEM30A in different systems, present current understanding of the protein structures and mechanisms of TMEM30A-P4-ATPase complexes, and discuss how these fundamental aspects of TMEM30A may be applied to disease treatment.
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Affiliation(s)
- Jingyi Li
- Key Laboratory of Medical Electrophysiology, Ministry of Education & Medical Electrophysiological Key Laboratory of Sichuan Province, Institute of Cardiovascular Research, Southwest Medical University, Luzhou, China
| | - Yue Zhao
- Clinical Medical Laboratory, Wenjiang Hospital of Sichuan Provincial People's Hospital, Chengdu, China
| | - Na Wang
- Key Laboratory of Medical Electrophysiology, Ministry of Education & Medical Electrophysiological Key Laboratory of Sichuan Province, Institute of Cardiovascular Research, Southwest Medical University, Luzhou, China
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20
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Arndt M, Alvadia C, Straub MS, Clerico Mosina V, Paulino C, Dutzler R. Structural basis for the activation of the lipid scramblase TMEM16F. Nat Commun 2022; 13:6692. [PMID: 36335104 PMCID: PMC9637102 DOI: 10.1038/s41467-022-34497-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2022] [Accepted: 10/26/2022] [Indexed: 11/06/2022] Open
Abstract
TMEM16F, a member of the conserved TMEM16 family, plays a central role in the initiation of blood coagulation and the fusion of trophoblasts. The protein mediates passive ion and lipid transport in response to an increase in intracellular Ca2+. However, the mechanism of how the protein facilitates both processes has remained elusive. Here we investigate the basis for TMEM16F activation. In a screen of residues lining the proposed site of conduction, we identify mutants with strongly activating phenotype. Structures of these mutants determined herein by cryo-electron microscopy show major rearrangements leading to the exposure of hydrophilic patches to the membrane, whose distortion facilitates lipid diffusion. The concomitant opening of a pore promotes ion conduction in the same protein conformation. Our work has revealed a mechanism that is distinct for this branch of the family and that will aid the development of a specific pharmacology for a promising drug target.
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Affiliation(s)
- Melanie Arndt
- grid.7400.30000 0004 1937 0650Department of Biochemistry University of Zurich, Winterthurer Str. 190, CH-8057 Zurich, Switzerland
| | - Carolina Alvadia
- grid.7400.30000 0004 1937 0650Department of Biochemistry University of Zurich, Winterthurer Str. 190, CH-8057 Zurich, Switzerland
| | - Monique S. Straub
- grid.7400.30000 0004 1937 0650Department of Biochemistry University of Zurich, Winterthurer Str. 190, CH-8057 Zurich, Switzerland
| | - Vanessa Clerico Mosina
- grid.4830.f0000 0004 0407 1981Department of Structural Biology and Membrane Enzymology at the Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 4, 9747 AG, Groningen, The Netherlands
| | - Cristina Paulino
- grid.4830.f0000 0004 0407 1981Department of Structural Biology and Membrane Enzymology at the Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 4, 9747 AG, Groningen, The Netherlands
| | - Raimund Dutzler
- grid.7400.30000 0004 1937 0650Department of Biochemistry University of Zurich, Winterthurer Str. 190, CH-8057 Zurich, Switzerland
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21
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Tang D, Wang Y, Dong X, Yuan Y, Kang F, Tian W, Wang K, Li H, Qi S. Scramblases and virus infection. Bioessays 2022; 44:e2100261. [DOI: 10.1002/bies.202100261] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Revised: 09/26/2022] [Accepted: 09/27/2022] [Indexed: 11/06/2022]
Affiliation(s)
- Dan Tang
- Department of Urology Institute of Urology (Laboratory of Reconstructive Urology) State Key Laboratory of Oral Disease West China Hospital of Stomatology West China Hospital Sichuan University Chengdu Sichuan China
| | - Yichang Wang
- Department of Urology Institute of Urology (Laboratory of Reconstructive Urology) State Key Laboratory of Oral Disease West China Hospital of Stomatology West China Hospital Sichuan University Chengdu Sichuan China
| | - Xiuju Dong
- Department of Urology Institute of Urology (Laboratory of Reconstructive Urology) State Key Laboratory of Oral Disease West China Hospital of Stomatology West China Hospital Sichuan University Chengdu Sichuan China
| | - Yiqiong Yuan
- Department of Urology Institute of Urology (Laboratory of Reconstructive Urology) State Key Laboratory of Oral Disease West China Hospital of Stomatology West China Hospital Sichuan University Chengdu Sichuan China
| | - Fanchen Kang
- Department of Urology Institute of Urology (Laboratory of Reconstructive Urology) State Key Laboratory of Oral Disease West China Hospital of Stomatology West China Hospital Sichuan University Chengdu Sichuan China
| | - Weidong Tian
- Department of Urology Institute of Urology (Laboratory of Reconstructive Urology) State Key Laboratory of Oral Disease West China Hospital of Stomatology West China Hospital Sichuan University Chengdu Sichuan China
| | - Kunjie Wang
- Department of Urology Institute of Urology (Laboratory of Reconstructive Urology) State Key Laboratory of Oral Disease West China Hospital of Stomatology West China Hospital Sichuan University Chengdu Sichuan China
| | - Hong Li
- Department of Urology Institute of Urology (Laboratory of Reconstructive Urology) State Key Laboratory of Oral Disease West China Hospital of Stomatology West China Hospital Sichuan University Chengdu Sichuan China
| | - Shiqian Qi
- Department of Urology Institute of Urology (Laboratory of Reconstructive Urology) State Key Laboratory of Oral Disease West China Hospital of Stomatology West China Hospital Sichuan University Chengdu Sichuan China
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22
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Jia Z, Huang J, Chen J. Activation of TMEM16F by inner gate charged mutations and possible lipid/ion permeation mechanisms. Biophys J 2022; 121:3445-3457. [PMID: 35978550 PMCID: PMC9515230 DOI: 10.1016/j.bpj.2022.08.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Revised: 05/24/2022] [Accepted: 08/12/2022] [Indexed: 11/19/2022] Open
Abstract
Transmembrane protein 16F (TMEM16F) is a ubiquitously expressed Ca2+-activated phospholipid scramblase that also functions as a largely non-selective ion channel. Though recent structural studies have revealed the closed and intermediate conformations of mammalian TMEM16F (mTMEM16F), the open and conductive state remains elusive. Instead, it has been proposed that an open hydrophilic pathway may not be required for lipid scrambling. We previously identified an inner activation gate, consisting of F518, Y563, and I612, and showed that charged mutations of the inner gate residues led to constitutively active mTMEM16F scrambling. Herein, atomistic simulations show that lysine substitution of F518 and Y563 can indeed lead to spontaneous opening of the permeation pore in the Ca2+-bound state of mTMEM16F. Dilation of the pore exposes hydrophilic patches in the upper pore region, greatly increases the pore hydration level, and enables lipid scrambling. The putative open state of mTMEM16F resembles the active state of fungal scramblases and is a meta-stable state for the wild-type protein in the Ca2+-bound state. Therefore, mTMEM16F may be capable of supporting the canonical in-groove scrambling mechanism in addition to the out-of-groove one. Further analysis reveals that the in-groove phospholipid and ion transduction pathways of mTMEM16F overlap from the intracellular side up to the inner gate but diverge from each other with different exits to the extracellular side of membrane.
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Affiliation(s)
- Zhiguang Jia
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts
| | - Jian Huang
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts
| | - Jianhan Chen
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts; Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, Massachusetts.
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Burata OE, Yeh TJ, Macdonald CB, Stockbridge RB. Still rocking in the structural era: a molecular overview of the Small Multidrug Resistance (SMR) transporter family. J Biol Chem 2022;:102482. [PMID: 36100040 DOI: 10.1016/j.jbc.2022.102482] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Revised: 08/24/2022] [Accepted: 09/07/2022] [Indexed: 11/20/2022] Open
Abstract
The small multidrug resistance (SMR) family is composed of widespread microbial membrane proteins that fulfill different transport functions. Four functional SMR subtypes have been identified, which variously transport the small, charged metabolite guanidinium, bulky hydrophobic drugs and antiseptics, polyamines, and glycolipids across the membrane bilayer. The transporters possess a minimalist architecture, with ∼100-residue subunits that require assembly into homodimers or heterodimers for transport. In part because of their simple construction, the SMRs are a tractable system for biochemical and biophysical analysis. Studies of SMR transporters over the last 25 years have yielded deep insights for diverse fields, including membrane protein topology and evolution, mechanisms of membrane transport, and bacterial multidrug resistance. Here, we review recent advances in understanding the structures and functions of SMR transporters. New molecular structures of SMRs representing two of the four functional subtypes reveal the conserved structural features that have permitted the emergence of disparate substrate transport functions in the SMR family and illuminate structural similarities with a distantly related membrane transporter family, SLC35/DMT.
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Abstract
The mechanoelectrical transduction (MET) channel in auditory hair cells converts sound into electrical signals, enabling hearing. Transmembrane-like channel 1 and 2 (TMC1 and TMC2) are implicated in forming the pore of the MET channel. Here, we demonstrate that inhibition of MET channels, breakage of the tip links required for MET, or buffering of intracellular Ca... induces pronounced phosphatidylserine externalization, membrane blebbing, and ectosome release at the hair cell sensory organelle, culminating in the loss of TMC1. Membrane homeostasis triggered by MET channel inhibition requires Tmc1 but not Tmc2, and three deafness-causing mutations in Tmc1 cause constitutive phosphatidylserine externalization that correlates with deafness phenotype. Our results suggest that, in addition to forming the pore of the MET channel, TMC1 is a critical regulator of membrane homeostasis in hair cells, and that Tmc1-related hearing loss may involve alterations in membrane homeostasis.
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Ma X, Li X, Wang W, Zhang M, Yang B, Miao Z. Phosphatidylserine, inflammation, and central nervous system diseases. Front Aging Neurosci 2022; 14:975176. [PMID: 35992593 PMCID: PMC9382310 DOI: 10.3389/fnagi.2022.975176] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Accepted: 07/15/2022] [Indexed: 11/13/2022] Open
Abstract
Phosphatidylserine (PS) is an anionic phospholipid in the eukaryotic membrane and is abundant in the brain. Accumulated studies have revealed that PS is involved in the multiple functions of the brain, such as activation of membrane signaling pathways, neuroinflammation, neurotransmission, and synaptic refinement. Those functions of PS are related to central nervous system (CNS) diseases. In this review, we discuss the metabolism of PS, the anti-inflammation function of PS in the brain; the alterations of PS in different CNS diseases, and the possibility of PS to serve as a therapeutic agent for diseases. Clinical studies have showed that PS has no side effects and is well tolerated. Therefore, PS and PS liposome could be a promising supplementation for these neurodegenerative and neurodevelopmental diseases.
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Affiliation(s)
- Xiaohua Ma
- Department of Neurology and Clinical Research Center of Neurological Disease, The Second Affiliated Hospital of Soochow University, Suzhou, China
- Institute of Neuroscience, Soochow University, Suzhou, China
| | - Xiaojing Li
- Suzhou Science and Technology Town Hospital, Suzhou, China
| | - Wenjuan Wang
- Institute of Neuroscience, Soochow University, Suzhou, China
| | - Meng Zhang
- Institute of Neuroscience, Soochow University, Suzhou, China
| | - Bo Yang
- Department of Anesthesiology, The Second Affiliated Hospital of Soochow University, Suzhou, China
- *Correspondence: Bo Yang,
| | - Zhigang Miao
- Department of Neurology and Clinical Research Center of Neurological Disease, The Second Affiliated Hospital of Soochow University, Suzhou, China
- Institute of Neuroscience, Soochow University, Suzhou, China
- Zhigang Miao,
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Affiliation(s)
- Hiroyuki Nakao
- Department of Biointerface Chemistry, Faculty of Pharmaceutical Sciences, University of Toyama
| | - Minoru Nakano
- Department of Biointerface Chemistry, Faculty of Pharmaceutical Sciences, University of Toyama
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Rodriguez TC, Zhong L, Simpson H, Gleason E. Reduced Expression of TMEM16A Impairs Nitric Oxide-Dependent Cl− Transport in Retinal Amacrine Cells. Front Cell Neurosci 2022; 16:937060. [PMID: 35966201 PMCID: PMC9363626 DOI: 10.3389/fncel.2022.937060] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Accepted: 06/21/2022] [Indexed: 11/13/2022] Open
Abstract
Postsynaptic cytosolic Cl− concentration determines whether GABAergic and glycinergic synapses are inhibitory or excitatory. We have shown that nitric oxide (NO) initiates the release of Cl− from acidic internal stores into the cytosol of retinal amacrine cells (ACs) thereby elevating cytosolic Cl−. In addition, we found that cystic fibrosis transmembrane conductance regulator (CFTR) expression and Ca2+ elevations are necessary for the transient effects of NO on cytosolic Cl− levels, but the mechanism remains to be elucidated. Here, we investigated the involvement of TMEM16A as a possible link between Ca2+ elevations and cytosolic Cl− release. TMEM16A is a Ca2+-activated Cl− channel that is functionally coupled with CFTR in epithelia. Both proteins are also expressed in neurons. Based on this and its Ca2+ dependence, we test the hypothesis that TMEM16A participates in the NO-dependent elevation in cytosolic Cl− in ACs. Chick retina ACs express TMEM16A as shown by Western blot analysis, single-cell PCR, and immunocytochemistry. Electrophysiology experiments demonstrate that TMEM16A functions in amacrine cells. Pharmacological inhibition of TMEM16A with T16inh-AO1 reduces the NO-dependent Cl− release as indicated by the diminished shift in the reversal potential of GABAA receptor-mediated currents. We confirmed the involvement of TMEM16A in the NO-dependent Cl− release using CRISPR/Cas9 knockdown of TMEM16A. Two different modalities targeting the gene for TMEM16A (ANO1) were tested in retinal amacrine cells: an all-in-one plasmid vector and crRNA/tracrRNA/Cas9 ribonucleoprotein. The all-in-one CRISPR/Cas9 modality did not change the expression of TMEM16A protein and produced no change in the response to NO. However, TMEM16A-specific crRNA/tracrRNA/Cas9 ribonucleoprotein effectively reduces both TMEM16A protein levels and the NO-dependent shift in the reversal potential of GABA-gated currents. These results show that TMEM16A plays a role in the NO-dependent Cl− release from retinal ACs.
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Al-Hosni R, Ilkan Z, Agostinelli E, Tammaro P. The pharmacology of the TMEM16A channel: therapeutic opportunities. Trends Pharmacol Sci 2022; 43:712-725. [PMID: 35811176 DOI: 10.1016/j.tips.2022.06.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Revised: 06/06/2022] [Accepted: 06/08/2022] [Indexed: 12/15/2022]
Abstract
The TMEM16A Ca2+-gated Cl- channel is involved in a variety of vital physiological functions and may be targeted pharmacologically for therapeutic benefit in diseases such as hypertension, stroke, and cystic fibrosis (CF). The determination of the TMEM16A structure and high-throughput screening efforts, alongside ex vivo and in vivo animal studies and clinical investigations, are hastening our understanding of the physiology and pharmacology of this channel. Here, we offer a critical analysis of recent developments in TMEM16A pharmacology and reflect on the therapeutic opportunities provided by this target.
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Affiliation(s)
- Rumaitha Al-Hosni
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK
| | - Zeki Ilkan
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK
| | - Emilio Agostinelli
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK
| | - Paolo Tammaro
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK.
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29
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Galietta LJ. TMEM16A (ANO1) as a therapeutic target in cystic fibrosis. Curr Opin Pharmacol 2022; 64:102206. [DOI: 10.1016/j.coph.2022.102206] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Revised: 02/15/2022] [Accepted: 02/17/2022] [Indexed: 01/02/2023]
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30
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Kleist TJ, Wudick MM. Shaping up: Recent advances in the study of plant calcium channels. Curr Opin Cell Biol 2022; 76:102080. [DOI: 10.1016/j.ceb.2022.102080] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Revised: 03/02/2022] [Accepted: 03/13/2022] [Indexed: 12/20/2022]
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Chrysanthou A, Ververis A, Christodoulou K. ANO10 Function in Health and Disease. Cerebellum 2022. [PMID: 35648332 DOI: 10.1007/s12311-022-01395-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 03/14/2022] [Indexed: 10/18/2022]
Abstract
Anoctamin 10 (ANO10), also known as TMEM16K, is a transmembrane protein and member of the anoctamin family characterized by functional duality. Anoctamins manifest ion channel and phospholipid scrambling activities and are involved in many physiological processes such as cell division, migration, apoptosis, cell signalling, and developmental processes. Several diseases, including neurological, muscle, blood disorders, and cancer, have been associated with the anoctamin family proteins. ANO10, which is the main focus of the present review, exhibits both scrambling and chloride channel activity; calcium availability is necessary for protein activation in either case. Additional processes implicating ANO10 include endosomal sorting, spindle assembly, and calcium signalling. Dysregulation of calcium signalling in Purkinje cells due to ANO10 defects is proposed as the main mechanism leading to spinocerebellar ataxia autosomal recessive type 10 (SCAR10), a rare, slowly progressive spinocerebellar ataxia. Regulation of the endolysosomal pathway is an additional ANO10 function linked to SCAR10 aetiology. Further functional investigation is essential to unravel the ANO10 mechanism of action and involvement in disease development.
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Falzone ME, Feng Z, Alvarenga OE, Pan Y, Lee B, Cheng X, Fortea E, Scheuring S, Accardi A. TMEM16 scramblases thin the membrane to enable lipid scrambling. Nat Commun 2022; 13:2604. [PMID: 35562175 PMCID: PMC9095706 DOI: 10.1038/s41467-022-30300-z] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Accepted: 04/25/2022] [Indexed: 12/14/2022] Open
Abstract
TMEM16 scramblases dissipate the plasma membrane lipid asymmetry to activate multiple eukaryotic cellular pathways. Scrambling was proposed to occur with lipid headgroups moving between leaflets through a membrane-spanning hydrophilic groove. Direct information on lipid-groove interactions is lacking. We report the 2.3 Å resolution cryogenic electron microscopy structure of the nanodisc-reconstituted Ca2+-bound afTMEM16 scramblase showing how rearrangement of individual lipids at the open pathway results in pronounced membrane thinning. Only the groove's intracellular vestibule contacts lipids, and mutagenesis suggests scrambling does not require specific protein-lipid interactions with the extracellular vestibule. We find scrambling can occur outside a closed groove in thinner membranes and is inhibited in thicker membranes, despite an open pathway. Our results show afTMEM16 thins the membrane to enable scrambling and that an open hydrophilic pathway is not a structural requirement to allow rapid transbilayer movement of lipids. This mechanism could be extended to other scramblases lacking a hydrophilic groove.
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Affiliation(s)
- Maria E Falzone
- Department of Anesthesiology, Weill Cornell Medical College, New York, NY, USA
- Department of Biochemistry, Weill Cornell Medical College, New York, NY, USA
| | - Zhang Feng
- Department of Anesthesiology, Weill Cornell Medical College, New York, NY, USA
| | - Omar E Alvarenga
- Department of Anesthesiology, Weill Cornell Medical College, New York, NY, USA
- Physiology, Biophysics and Systems Biology Graduate Program, Weill Cornell Medical College, New York, NY, USA
| | - Yangang Pan
- Department of Anesthesiology, Weill Cornell Medical College, New York, NY, USA
| | - ByoungCheol Lee
- Department of Anesthesiology, Weill Cornell Medical College, New York, NY, USA
- Neurovascular Unit Research Group, Korea Brain Research Institute (KBRI), Daegu, 41062, Republic of Korea
| | - Xiaolu Cheng
- Department of Physiology and Biophysics, Weill Cornell Medical College, New York, NY, USA
| | - Eva Fortea
- Department of Anesthesiology, Weill Cornell Medical College, New York, NY, USA
- Physiology, Biophysics and Systems Biology Graduate Program, Weill Cornell Medical College, New York, NY, USA
| | - Simon Scheuring
- Department of Anesthesiology, Weill Cornell Medical College, New York, NY, USA
| | - Alessio Accardi
- Department of Anesthesiology, Weill Cornell Medical College, New York, NY, USA.
- Department of Biochemistry, Weill Cornell Medical College, New York, NY, USA.
- Department of Physiology and Biophysics, Weill Cornell Medical College, New York, NY, USA.
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Behuria HG, Dash S, Sahu SK. Phospholipid Scramblases: Role in Cancer Progression and Anticancer Therapeutics. Front Genet 2022; 13:875894. [PMID: 35422844 PMCID: PMC9002267 DOI: 10.3389/fgene.2022.875894] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Accepted: 03/11/2022] [Indexed: 11/13/2022] Open
Abstract
Phospholipid scramblases (PLSCRs) that catalyze rapid mixing of plasma membrane lipids result in surface exposure of phosphatidyl serine (PS), a lipid normally residing to the inner plasma membrane leaflet. PS exposure provides a chemotactic eat-me signal for phagocytes resulting in non-inflammatory clearance of apoptotic cells by efferocytosis. However, metastatic tumor cells escape efferocytosis through alteration of tumor microenvironment and apoptotic signaling. Tumor cells exhibit altered membrane features, high constitutive PS exposure, low drug permeability and increased multidrug resistance through clonal evolution. PLSCRs are transcriptionally up-regulated in tumor cells leading to plasma membrane remodeling and aberrant PS exposure on cell surface. In addition, PLSCRs interact with multiple cellular components to modulate cancer progression and survival. While PLSCRs and PS exposed on tumor cells are novel drug targets, many exogenous molecules that catalyze lipid scrambling on tumor plasma membrane are potent anticancer therapeutic molecules. In this review, we provide a comprehensive analysis of scramblase mediated signaling events, membrane alteration specific to tumor development and possible therapeutic implications of scramblases and PS exposure.
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Affiliation(s)
- Himadri Gourav Behuria
- Laboratory of Molecular Membrane Biology, Department of Biotechnology, Maharaja Sriram Chandra Bhanjadeo University, Baripada, India
| | - Sabyasachi Dash
- Department of Pathology and Laboratory Medicine, Weill Cornell Medicine, New York, NY, United States
| | - Santosh Kumar Sahu
- Laboratory of Molecular Membrane Biology, Department of Biotechnology, Maharaja Sriram Chandra Bhanjadeo University, Baripada, India
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Reiss K, Leitzke S, Seidel J, Sperrhacke M, Bhakdi S. Scramblases as Regulators of Proteolytic ADAM Function. Membranes 2022; 12:185. [PMID: 35207106 PMCID: PMC8880048 DOI: 10.3390/membranes12020185] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Revised: 01/25/2022] [Accepted: 02/02/2022] [Indexed: 11/16/2022]
Abstract
Proteolytic ectodomain release is a key mechanism for regulating the function of many cell surface proteins. The sheddases ADAM10 and ADAM17 are the best-characterized members of the family of transmembrane disintegrin-like metalloproteinase. Constitutive proteolytic activities are low but can be abruptly upregulated via inside-out signaling triggered by diverse activating events. Emerging evidence indicates that the plasma membrane itself must be assigned a dominant role in upregulation of sheddase function. Data are discussed that tentatively identify phospholipid scramblases as central players during these events. We propose that scramblase-dependent externalization of the negatively charged phospholipid phosphatidylserine (PS) plays an important role in the final activation step of ADAM10 and ADAM17. In this manuscript, we summarize the current knowledge on the interplay of cell membrane changes, PS exposure, and proteolytic activity of transmembrane proteases as well as the potential consequences in the context of immune response, infection, and cancer. The novel concept that scramblases regulate the action of ADAM-proteases may be extendable to other functional proteins that act at the cell surface.
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35
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Agostinelli E, Tammaro P. Polymodal Control of TMEM16x Channels and Scramblases. Int J Mol Sci 2022; 23:1580. [PMID: 35163502 PMCID: PMC8835819 DOI: 10.3390/ijms23031580] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2021] [Revised: 01/20/2022] [Accepted: 01/20/2022] [Indexed: 02/01/2023] Open
Abstract
The TMEM16A/anoctamin-1 calcium-activated chloride channel (CaCC) contributes to a range of vital functions, such as the control of vascular tone and epithelial ion transport. The channel is a founding member of a family of 10 proteins (TMEM16x) with varied functions; some members (i.e., TMEM16A and TMEM16B) serve as CaCCs, while others are lipid scramblases, combine channel and scramblase function, or perform additional cellular roles. TMEM16x proteins are typically activated by agonist-induced Ca2+ release evoked by Gq-protein-coupled receptor (GqPCR) activation; thus, TMEM16x proteins link Ca2+-signalling with cell electrical activity and/or lipid transport. Recent studies demonstrate that a range of other cellular factors—including plasmalemmal lipids, pH, hypoxia, ATP and auxiliary proteins—also control the activity of the TMEM16A channel and its paralogues, suggesting that the TMEM16x proteins are effectively polymodal sensors of cellular homeostasis. Here, we review the molecular pathophysiology, structural biology, and mechanisms of regulation of TMEM16x proteins by multiple cellular factors.
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36
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Leitzke S, Seidel J, Ahrens B, Schreiber R, Kunzelmann K, Sperrhacke M, Bhakdi S, Reiss K. Influence of Anoctamin-4 and -9 on ADAM10 and ADAM17 Sheddase Function. Membranes 2022; 12:membranes12020123. [PMID: 35207044 PMCID: PMC8879676 DOI: 10.3390/membranes12020123] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Revised: 01/18/2022] [Accepted: 01/19/2022] [Indexed: 02/04/2023]
Abstract
Ca2+-activated Cl− channels (TMEM16, also known as anoctamins) perform important functions in cell physiology, including modulation of cell proliferation and cancer growth. Many members, including TMEM16F/ANO6, additionally act as Ca2+-activated phospholipid scramblases. We recently presented evidence that ANO6-dependent surface exposure of phosphatidylserine (PS) is pivotal for the disintegrin-like metalloproteases ADAM10 and ADAM17 to exert their sheddase function. Here, we compared the influence of seven ANO family members (ANO1, 4, 5, 6, 7, 9, and 10) on ADAM sheddase activity. Similar to ANO6, overexpression of ANO4 and ANO9 led to increased release of ADAM10 and ADAM17 substrates, such as betacellulin, TGFα, and amphiregulin (AREG), upon ionophore stimulation in HEK cells. Inhibitor experiments indicated that ANO4/ANO9-mediated enhancement of TGFα-cleavage broadened the spectrum of participating metalloproteinases. Annexin V-staining demonstrated increased externalisation of PS in ANO4/ANO9-overexpressing cells. Competition experiments with the soluble PS-headgroup phosphorylserine indicated that the ANO4/ANO9 effects were due to increased PS exposure. Overexpression of ANO4 or ANO9 in human cervical cancer cells (HeLa), enhanced constitutive shedding of the growth factor AREG and increased cell proliferation. We conclude that ANO4 and ANO9, by virtue of their scramblase activity, may play a role as important regulators of ADAM-dependent cellular functions.
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Affiliation(s)
- Sinje Leitzke
- Department of Dermatology, University of Kiel, 24105 Kiel, Germany; (S.L.); (J.S.); (B.A.); (M.S.)
| | - Jana Seidel
- Department of Dermatology, University of Kiel, 24105 Kiel, Germany; (S.L.); (J.S.); (B.A.); (M.S.)
| | - Björn Ahrens
- Department of Dermatology, University of Kiel, 24105 Kiel, Germany; (S.L.); (J.S.); (B.A.); (M.S.)
| | - Rainer Schreiber
- Physiological Institute, University of Regensburg, Universitätsstraße 31, 93053 Regensburg, Germany; (R.S.); (K.K.)
| | - Karl Kunzelmann
- Physiological Institute, University of Regensburg, Universitätsstraße 31, 93053 Regensburg, Germany; (R.S.); (K.K.)
| | - Maria Sperrhacke
- Department of Dermatology, University of Kiel, 24105 Kiel, Germany; (S.L.); (J.S.); (B.A.); (M.S.)
| | | | - Karina Reiss
- Department of Dermatology, University of Kiel, 24105 Kiel, Germany; (S.L.); (J.S.); (B.A.); (M.S.)
- Correspondence:
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Abstract
Rapid flip-flop of phospholipids across the two leaflets of biological membranes is crucial for many aspects of cellular life. The transport proteins that facilitate this process are classified as pump-like flippases and floppases and channel-like scramblases. Unexpectedly, Class A G protein-coupled receptors (GPCRs), a large class of signaling proteins exemplified by the visual receptor rhodopsin and its apoprotein opsin, are constitutively active as scramblases in vitro. In liposomes, opsin scrambles lipids at a unitary rate of >100,000 per second. Atomistic molecular dynamics simulations of opsin in a lipid membrane reveal conformational transitions that expose a polar groove between transmembrane helices 6 and 7. This groove enables transbilayer lipid movement, conceptualized as the swiping of a credit card (lipid) through a card reader (GPCR). Conformational changes that facilitate scrambling are distinct from those associated with GPCR signaling. In this review, we discuss the physiological significance of GPCR scramblase activity and the modes of its regulation in cells. Expected final online publication date for the Annual Review of Biophysics, Volume 51 is May 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- George Khelashvili
- Department of Physiology and Biophysics, Weill Cornell Medical College, New York, New York, USA; .,Institute of Computational Biomedicine, Weill Cornell Medical College, New York, New York, USA
| | - Anant K Menon
- Department of Biochemistry, Weill Cornell Medical College, New York, New York, USA;
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38
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Wray S, Prendergast C, Arrowsmith S. Calcium-Activated Chloride Channels in Myometrial and Vascular Smooth Muscle. Front Physiol 2021; 12:751008. [PMID: 34867456 PMCID: PMC8637852 DOI: 10.3389/fphys.2021.751008] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Accepted: 09/24/2021] [Indexed: 11/24/2022] Open
Abstract
In smooth muscle tissues, calcium-activated chloride channels (CaCC) provide the major anionic channel. Opening of these channels leads to chloride efflux and depolarization of the myocyte membrane. In this way, activation of the channels by a rise of intracellular [Ca2+], from a variety of sources, produces increased excitability and can initiate action potentials and contraction or increased tone. We now have a good mechanistic understanding of how the channels are activated and regulated, due to identification of TMEM16A (ANO1) as the molecular entity of the channel, but key questions remain. In reviewing these channels and comparing two distinct smooth muscles, myometrial and vascular, we expose the differences that occur in their activation mechanisms, properties, and control. We find that the myometrium only expresses “classical,” Ca2+-activated, and voltage sensitive channels, whereas both tonic and phasic blood vessels express classical, and non-classical, cGMP-regulated CaCC, which are voltage insensitive. This translates to more complex activation and regulation in vascular smooth muscles, irrespective of whether they are tonic or phasic. We therefore tentatively conclude that although these channels are expressed and functionally important in all smooth muscles, they are probably not part of the mechanisms governing phasic activity. Recent knockdown studies have produced unexpected functional results, e.g. no effects on labour and delivery, and tone increasing in some but decreasing in other vascular beds, strongly suggesting that there is still much to be explored concerning CaCC in smooth muscle.
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Affiliation(s)
- Susan Wray
- Department of Women and Children's Health, Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, United Kingdom
| | - Clodagh Prendergast
- Department of Women and Children's Health, Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, United Kingdom
| | - Sarah Arrowsmith
- Department of Life Sciences, Manchester Metropolitan University, Manchester, United Kingdom
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Hawn MB, Akin E, Hartzell H, Greenwood IA, Leblanc N. Molecular mechanisms of activation and regulation of ANO1-Encoded Ca 2+-Activated Cl - channels. Channels (Austin) 2021; 15:569-603. [PMID: 34488544 PMCID: PMC8480199 DOI: 10.1080/19336950.2021.1975411] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Accepted: 08/29/2021] [Indexed: 01/13/2023] Open
Abstract
Ca2+-activated Cl- channels (CaCCs) perform a multitude of functions including the control of cell excitability, regulation of cell volume and ionic homeostasis, exocrine and endocrine secretion, fertilization, amplification of olfactory sensory function, and control of smooth muscle cell contractility. CaCCs are the translated products of two members (ANO1 and ANO2, also known as TMEM16A and TMEM16B) of the Anoctamin family of genes comprising ten paralogs. This review focuses on recent progress in understanding the molecular mechanisms involved in the regulation of ANO1 by cytoplasmic Ca2+, post-translational modifications, and how the channel protein interacts with membrane lipids and protein partners. After first reviewing the basic properties of native CaCCs, we then present a brief historical perspective highlighting controversies about their molecular identity in native cells. This is followed by a summary of the fundamental biophysical and structural properties of ANO1. We specifically address whether the channel is directly activated by internal Ca2+ or indirectly through the intervention of the Ca2+-binding protein Calmodulin (CaM), and the structural domains responsible for Ca2+- and voltage-dependent gating. We then review the regulation of ANO1 by internal ATP, Calmodulin-dependent protein kinase II-(CaMKII)-mediated phosphorylation and phosphatase activity, membrane lipids such as the phospholipid phosphatidyl-(4,5)-bisphosphate (PIP2), free fatty acids and cholesterol, and the cytoskeleton. The article ends with a survey of physical and functional interactions of ANO1 with other membrane proteins such as CLCA1/2, inositol trisphosphate and ryanodine receptors in the endoplasmic reticulum, several members of the TRP channel family, and the ancillary Κ+ channel β subunits KCNE1/5.
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Affiliation(s)
- M. B. Hawn
- Department of Pharmacology and Center of Biomedical Research Excellence for Molecular and Cellular Signal Transduction in the Cardiovascular System, University of Nevada, Reno School of Medicine, Reno, United States
| | - E. Akin
- Department of Pharmacology and Center of Biomedical Research Excellence for Molecular and Cellular Signal Transduction in the Cardiovascular System, University of Nevada, Reno School of Medicine, Reno, United States
| | - H.C. Hartzell
- Department of Cell Biology, Emory University School of Medicine, USA
| | - I. A. Greenwood
- Department of Vascular Pharmacology, St. George’s University of London, UK
| | - N. Leblanc
- Department of Pharmacology and Center of Biomedical Research Excellence for Molecular and Cellular Signal Transduction in the Cardiovascular System, University of Nevada, Reno School of Medicine, Reno, United States
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Abstract
The transmembrane protein 16 (TMEM16) family consists of Ca2+-activated ion channels and Ca2+-activated phospholipid scramblases (CaPLSases) that passively flip-flop phospholipids between the two leaflets of the membrane bilayer. Owing to their diverse functions, TMEM16 proteins have been implicated in various human diseases, including asthma, cancer, bleeding disorders, muscular dystrophy, arthritis, epilepsy, dystonia, ataxia, and viral infection. To understand TMEM16 proteins in health and disease, it is critical to decipher their molecular mechanisms of activation gating and regulation. Structural, biophysical, and computational characterizations over the past decade have greatly advanced the molecular understanding of TMEM16 proteins. In this review, we summarize major structural features of the TMEM16 proteins with a focus on regulatory mechanisms and gating.
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Affiliation(s)
- Son C. Le
- Department of Biochemistry, Duke University Medical Center, Durham, NC, United States
| | - Pengfei Liang
- Department of Biochemistry, Duke University Medical Center, Durham, NC, United States
| | - Augustus J. Lowry
- Department of Biochemistry, Duke University Medical Center, Durham, NC, United States
| | - Huanghe Yang
- Department of Biochemistry, Duke University Medical Center, Durham, NC, United States
- Department of Neurobiology, Duke University Medical Center, Durham, NC, United States
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41
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Pifferi S, Menini A. Paving the way for designing drugs targeting TMEM16A. Trends Pharmacol Sci 2021; 42:979-980. [PMID: 34696895 DOI: 10.1016/j.tips.2021.10.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 10/08/2021] [Accepted: 10/11/2021] [Indexed: 11/24/2022]
Abstract
The calcium-activated chloride channel TMEM16A is involved in several physiological processes and is an important pharmacological target. Dinsdale and colleagues recently unveiled several residues in the outer pore region that constitute a critical site for the design of drugs that modulate TMEM16A channels.
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Affiliation(s)
- Simone Pifferi
- Department of Experimental and Clinical Medicine, Università Politecnica delle Marche, 60126 Ancona, Italy
| | - Anna Menini
- Neurobiology Group, SISSA, Scuola Internazionale Superiore di Studi Avanzati, 34136 Trieste, Italy.
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42
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Lenoir G, D'Ambrosio JM, Dieudonné T, Čopič A. Transport Pathways That Contribute to the Cellular Distribution of Phosphatidylserine. Front Cell Dev Biol 2021; 9:737907. [PMID: 34540851 PMCID: PMC8440936 DOI: 10.3389/fcell.2021.737907] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Accepted: 08/10/2021] [Indexed: 12/05/2022] Open
Abstract
Phosphatidylserine (PS) is a negatively charged phospholipid that displays a highly uneven distribution within cellular membranes, essential for establishment of cell polarity and other processes. In this review, we discuss how combined action of PS biosynthesis enzymes in the endoplasmic reticulum (ER), lipid transfer proteins (LTPs) acting within membrane contact sites (MCS) between the ER and other compartments, and lipid flippases and scramblases that mediate PS flip-flop between membrane leaflets controls the cellular distribution of PS. Enrichment of PS in specific compartments, in particular in the cytosolic leaflet of the plasma membrane (PM), requires input of energy, which can be supplied in the form of ATP or by phosphoinositides. Conversely, coupling between PS synthesis or degradation, PS flip-flop and PS transfer may enable PS transfer by passive flow. Such scenario is best documented by recent work on the formation of autophagosomes. The existence of lateral PS nanodomains, which is well-documented in the case of the PM and postulated for other compartments, can change the steepness or direction of PS gradients between compartments. Improvements in cellular imaging of lipids and membranes, lipidomic analysis of complex cellular samples, reconstitution of cellular lipid transport reactions and high-resolution structural data have greatly increased our understanding of cellular PS homeostasis. Our review also highlights how budding yeast has been instrumental for our understanding of the organization and transport of PS in cells.
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Affiliation(s)
- Guillaume Lenoir
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell, Gif-sur-Yvette, France
| | - Juan Martín D'Ambrosio
- Centre de Recherche en Biologie Cellulaire de Montpellier (CRBM), Université de Montpellier, CNRS, Montpellier, France
| | - Thibaud Dieudonné
- Danish Research Institute of Translational Neuroscience - DANDRITE, Nordic EMBL Partnership for Molecular Medicine, Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
| | - Alenka Čopič
- Centre de Recherche en Biologie Cellulaire de Montpellier (CRBM), Université de Montpellier, CNRS, Montpellier, France
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Abstract
Mechanosensitive ion channels mediate the neuronal sensation of mechanical signals such as sound, touch, and pain. Recent studies point to a function of these channel proteins in cell types and tissues in addition to the nervous system, such as epithelia, where they have been little studied, and their role has remained elusive. Dynamic epithelia are intrinsically exposed to mechanical forces. A response to pull and push is assumed to constitute an essential part of morphogenetic movements of epithelial tissues, for example. Mechano-gated channels may participate in sensing and responding to such forces. In this review, focusing on Drosophila, we highlight recent results that will guide further investigations concerned with the mechanistic role of these ion channels in epithelial cells.
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Stabilini S, Menini A, Pifferi S. Anion and Cation Permeability of the Mouse TMEM16F Calcium-Activated Channel. Int J Mol Sci 2021; 22:8578. [PMID: 34445284 DOI: 10.3390/ijms22168578] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Revised: 07/31/2021] [Accepted: 08/04/2021] [Indexed: 12/27/2022] Open
Abstract
TMEM16F is involved in several physiological processes, such as blood coagulation, bone development and virus infections. This protein acts both as a Ca2+-dependent phospholipid scramblase and a Ca2+-activated ion channel but several studies have reported conflicting results about the ion selectivity of the TMEM16F-mediated current. Here, we have performed a detailed side-by-side comparison of the ion selectivity of TMEM16F using the whole-cell and inside-out excised patch configurations to directly compare the results. In inside-out configuration, Ca2+-dependent activation was fast and the TMEM16F-mediated current was activated in a few milliseconds, while in whole-cell recordings full activation required several minutes. We determined the relative permeability between Na+ and Cl¯ (PNa/PCl) using the dilution method in both configurations. The TMEM16F-mediated current was highly nonselective, but there were differences depending on the configuration of the recordings. In whole-cell recordings, PNa/PCl was approximately 0.5, indicating a slight preference for Cl¯ permeation. In contrast, in inside-out experiments the TMEM16F channel showed a higher permeability for Na+ with PNa/PCl reaching 3.7. Our results demonstrate that the time dependence of Ca2+ activation and the ion selectivity of TMEM16F depend on the recording configuration.
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45
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Straub MS, Alvadia C, Sawicka M, Dutzler R. Cryo-EM structures of the caspase-activated protein XKR9 involved in apoptotic lipid scrambling. eLife 2021; 10:e69800. [PMID: 34263724 PMCID: PMC8298096 DOI: 10.7554/elife.69800] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Accepted: 07/11/2021] [Indexed: 12/17/2022] Open
Abstract
The exposure of the negatively charged lipid phosphatidylserine on the cell surface, catalyzed by lipid scramblases, is an important signal for the clearance of apoptotic cells by macrophages. The protein XKR9 is a member of a conserved family that has been associated with apoptotic lipid scrambling. Here, we describe structures of full-length and caspase-treated XKR9 from Rattus norvegicus in complex with a synthetic nanobody determined by cryo-electron microscopy. The 43 kDa monomeric membrane protein can be divided into two structurally related repeats, each containing four membrane-spanning segments and a helix that is partly inserted into the lipid bilayer. In the full-length protein, the C-terminus interacts with a hydrophobic pocket located at the intracellular side acting as an inhibitor of protein function. Cleavage by caspase-3 at a specific site releases 16 residues of the C-terminus, thus making the pocket accessible to the cytoplasm. Collectively, the work has revealed the unknown architecture of the XKR family and has provided initial insight into its activation by caspases.
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Affiliation(s)
- Monique S Straub
- Department of Biochemistry, University of ZurichZurichSwitzerland
| | - Carolina Alvadia
- Department of Biochemistry, University of ZurichZurichSwitzerland
| | - Marta Sawicka
- Department of Biochemistry, University of ZurichZurichSwitzerland
| | - Raimund Dutzler
- Department of Biochemistry, University of ZurichZurichSwitzerland
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Wang T, Wang H, Yang F, Gao K, Luo S, Bai L, Ma K, Liu M, Wu S, Wang H, Chen Z, Xiao Q. Honokiol inhibits proliferation of colorectal cancer cells by targeting anoctamin 1/TMEM16A Ca 2+ -activated Cl - channels. Br J Pharmacol 2021; 178:4137-4154. [PMID: 34192810 DOI: 10.1111/bph.15606] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Revised: 05/25/2021] [Accepted: 06/06/2021] [Indexed: 12/29/2022] Open
Abstract
BACKGROUND AND PURPOSE Ca2+ -activated Cl- channels (Ano1 channels) contribute to the pathogenesis of colorectal cancer. Honokiol is known to inhibit cell proliferation and tumour growth in colorectal cancer. However, the molecular target of honokiol remains unclear. This study aimed to investigate whether honokiol inhibited cell proliferation of colorectal cancer by targeting Ano1 channels. EXPERIMENTAL APPROACH Patch-clamp techniques were performed to study the effect of honokiol on Ca2+ -activated Cl- currents in HEK293 cells overexpressing Ano1- or Ano2-containing plasmids or in human colorectal carcinoma SW620 cells. Site-directed mutagenesis was used to identify the critical residues for honokiol-induced Ano1 inhibition. Proliferation of SW620 cells or human intestinal epithelial NCM460 cells by CCK-8 assays. KEY RESULTS Honokiol blocked Ano1 currents in Ano1-overexpressing HEK293 cells and SW620 cells. Honokiol more potently inhibited Ano1 currents than Ano2 currents. Three amino acids (R429, K430 and N435) were critical for honokiol-induced Ano1 inhibition. The R429A/K430L/N435G mutation reduced the sensitivity of Ano1 to honokiol. Honokiol inhibited SW620 cell proliferation, and this effect was reduced by Ano1-shRNAs. Furthermore, Ano1 overexpression promoted proliferation in NCM460 cells with low Ano1 endogenous expression and resulted in an increased sensitivity to honokiol. Overexpression of the R429A/K430L/N435G mutation reduced WT Ano1-induced increase in the sensitivity of NCM460 cells to honokiol. CONCLUSION AND IMPLICATIONS We identified a new anticancer mechanism of honokiol, through the inhibition of cell proliferation, by targeting Ano1 Ca2+ -activated Cl- channels.
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Affiliation(s)
- Tianyu Wang
- Department of Ion Channel Pharmacology, School of Pharmacy, China Medical University, Shenyang, China
| | - Hui Wang
- Department of Ion Channel Pharmacology, School of Pharmacy, China Medical University, Shenyang, China
| | - Fan Yang
- Department of Ion Channel Pharmacology, School of Pharmacy, China Medical University, Shenyang, China
| | - Kuan Gao
- Department of Ion Channel Pharmacology, School of Pharmacy, China Medical University, Shenyang, China
| | - Shuya Luo
- Department of Ion Channel Pharmacology, School of Pharmacy, China Medical University, Shenyang, China
| | - Lichuan Bai
- Department of Ion Channel Pharmacology, School of Pharmacy, China Medical University, Shenyang, China
| | - Ke Ma
- Department of Ion Channel Pharmacology, School of Pharmacy, China Medical University, Shenyang, China
| | - Mei Liu
- Department of Ion Channel Pharmacology, School of Pharmacy, China Medical University, Shenyang, China
| | - Shuwei Wu
- Department of Ion Channel Pharmacology, School of Pharmacy, China Medical University, Shenyang, China
| | - Huijie Wang
- Department of Ion Channel Pharmacology, School of Pharmacy, China Medical University, Shenyang, China
| | - Zaixing Chen
- Pharmaceutical Teaching and Experimental Center, School of Pharmacy, China Medical University, Shenyang, China
| | - Qinghuan Xiao
- Department of Ion Channel Pharmacology, School of Pharmacy, China Medical University, Shenyang, China
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Affiliation(s)
- Randy B Stockbridge
- Department of Molecular, Cellular and Developmental Biology and Program in Biophysics, University of Michigan, Ann Arbor, MI 48109, USA
| | - Rachelle Gaudet
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA
| | - Michael Grabe
- Cardiovascular Research Institute, University of California, San Francisco, CA 94158, USA; Department of Pharmaceutical Chemistry, University of California, San Francisco, CA 94158, USA
| | - Daniel L Minor
- Cardiovascular Research Institute, University of California, San Francisco, CA 94158, USA; Departments of Biochemsitry and Biophysics, and Cellular and Molecular Pharmacology, University of California, San Francisco, CA 94158, USA; California Institute for Quantiative Biomedical Research, University of California, San Francisco, CA 94158, USA; Kavli Institute for Fundamental Neuroscience University of California, San Francisco, CA 93858-2330, USA; Molecular Biophysics and Integrated Bio-imaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
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